[UPDATE 7/13/14, 2:25 pm]: The man who killed rookie cop Melvin Santiago was reportedly "laying in wait" for police, "telling a witness to watch the news because he was 'going to be famous,'" the AP reports. Lawrence Campbell, 27, never tried to rob the Walgreens, but instead assaulted a security guard in the store with a knife, stealing his gun, which was reportedly used to then shoot Santiago in the head.

Santiago responded to a call at a Walgreens at around 4 a.m. Sunday morning. According to a witness, when Santiago and his partner arrived to the store, the robbery suspect came out shooting.

Via the Associated Press:

Jean Belviso, who has been delivering newspapers for 10 years, was driving through the Walgreens parking lot when she said saw a man wearing burgundy sweatpants and a baseball cap walk out of Walgreens. A police cruiser pulled up in front of the store, and the suspect began shooting, the 61-year-old Belviso said.

"We thought he was running, coming toward us," said Belviso, who was riding along with a friend. "He kept on shooting."

Additional officers, who had responded to the robbery call, arrived and shot the robbery suspect. According to the AP, the man's body lay out for four hours before police officers pulled a tent over him.

This was the first cop killing in Jersey City since 2009, Mayor Fulop said in his statement.